linux-toradex.git/arch/x86/kernel/paravirt_patch_32.c, branch v3.2.55 Linux kernel for Apalis and Colibri modules x86/pvops: add a paravirt_ident functions to allow special patching 2009-01-30T22:51:44+00:00 Jeremy Fitzhardinge jeremy@goop.org 2009-01-28T22:35:02+00:00 41edafdb78feac1d1f8823846209975fde990633 Impact: Optimization Several paravirt ops implementations simply return their arguments, the most obvious being the make_pte/pte_val class of operations on native. On 32-bit, the identity function is literally a no-op, as the calling convention uses the same registers for the first argument and return. On 64-bit, it can be implemented with a single "mov". This patch adds special identity functions for 32 and 64 bit argument, and machinery to recognize them and replace them with either nops or a mov as appropriate. At the moment, the only users for the identity functions are the pagetable entry conversion functions. The result is a measureable improvement on pagetable-heavy benchmarks (2-3%, reducing the pvops overhead from 5 to 2%). Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com> 
Impact: Optimization

Several paravirt ops implementations simply return their arguments,
the most obvious being the make_pte/pte_val class of operations on
native.

On 32-bit, the identity function is literally a no-op, as the calling
convention uses the same registers for the first argument and return.
On 64-bit, it can be implemented with a single "mov".

This patch adds special identity functions for 32 and 64 bit argument,
and machinery to recognize them and replace them with either nops or a
mov as appropriate.

At the moment, the only users for the identity functions are the
pagetable entry conversion functions.

The result is a measureable improvement on pagetable-heavy benchmarks
(2-3%, reducing the pvops overhead from 5 to 2%).

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
x86: coding style fixes to arch/x86/kernel/paravirt_patch_32.c 2008-08-15T14:53:25+00:00 Paolo Ciarrocchi paolo.ciarrocchi@gmail.com 2008-08-02T19:25:43+00:00 d9336a9b47d57db835453968efbd0d5cedfe0260 Before: total: 3 errors, 1 warnings, 49 lines checked After: total: 2 errors, 1 warnings, 49 lines checked paolo@paolo-desktop:~/linux.trees.git$ md5sum /tmp/paravirt_patch_32.o.* a78eea4264723e18c49dcfbe0ee0aae7 /tmp/paravirt_patch_32.o.after a78eea4264723e18c49dcfbe0ee0aae7 /tmp/paravirt_patch_32.o.before Signed-off-by: Paolo Ciarrocchi <paolo.ciarrocchi@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> 
Before:
total: 3 errors, 1 warnings, 49 lines checked

After:
total: 2 errors, 1 warnings, 49 lines checked

paolo@paolo-desktop:~/linux.trees.git$ md5sum /tmp/paravirt_patch_32.o.*
a78eea4264723e18c49dcfbe0ee0aae7  /tmp/paravirt_patch_32.o.after
a78eea4264723e18c49dcfbe0ee0aae7  /tmp/paravirt_patch_32.o.before

Signed-off-by: Paolo Ciarrocchi <paolo.ciarrocchi@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
x86/paravirt: split sysret and sysexit 2008-07-08T11:13:15+00:00 Jeremy Fitzhardinge jeremy@goop.org 2008-06-25T04:19:26+00:00 d75cd22fdd5f7d203fb60014d426942df33dd9a6 Don't conflate sysret and sysexit; they're different instructions with different semantics, and may be in use at the same time (at least within the same kernel, depending on whether its an Intel or AMD system). sysexit - just return to userspace, does no register restoration of any kind; must explicitly atomically enable interrupts. sysret - reloads flags from r11, so no need to explicitly enable interrupts on 64-bit, responsible for restoring usermode %gs Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citirx.com> Cc: xen-devel <xen-devel@lists.xensource.com> Cc: Stephen Tweedie <sct@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> 
Don't conflate sysret and sysexit; they're different instructions with
different semantics, and may be in use at the same time (at least
within the same kernel, depending on whether its an Intel or AMD
system).

sysexit - just return to userspace, does no register restoration of
    any kind; must explicitly atomically enable interrupts.

sysret - reloads flags from r11, so no need to explicitly enable
    interrupts on 64-bit, responsible for restoring usermode %gs

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citirx.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
x86: move patching code to arch-specific file. 2008-01-30T12:32:10+00:00 Glauber de Oliveira Costa gcosta@redhat.com 2008-01-30T12:32:10+00:00 2f485ef568372af4680c4e2f8490efb9f2523b05 The core patching code for paravirt is sufficiently different among i386 and x86_64, and we move them to specific files. Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
The core patching code for paravirt is sufficiently different
among i386 and x86_64, and we move them to specific files.

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>